The invention relates to an X-ray diagnostic installation, comprising a television pickup system, comprising a first image memory, comprising a difference stage for providing subtraction images through difference formation from the stored and the current video signals, and comprising a monitor, wherein an adder is connected with the output of the difference stage, which adder is connected with a second image memory whose output signal is supplied to the adder so that, in the second image memory, the image point data of the difference stage are summed up, and wherein the output signal of the second image memory is supplied to the monitor. Diagnostic installations of this type are employed for the purpose of subtraction of X-ray images in real time.
In the case of the X-ray diagnostic installation of the type initially cited according to German application P 30 18 129.4 (U.S. Pat. No. 4,398,213 issued Aug. 9, 1983), a subtraction between the video signal of a stored image, representing a mask, and the video signal of an immediate image is conducted. The stored video signal corresponds, in particular, to a blank image (without contrast medium), whereas the current or immediate video signals represent filling images with contrast medium. For the representation of the entire contrast medium flow the difference signals are superimposed in the second image memory so that after completion of the examination the entire filling image is shown on the monitor.